The recent acquittal of four Boston Teamsters charged with attempting to extort the producers of the popular “Top Chef” television show is the latest illustration of a loophole in federal law that permits organized labor to engage in acts of extortion that would be illegal if anyone else tried it.

Since a 1973 Supreme Court decision exempted union extortion and racketeering actions from the Hobbs Act, so long as the object being extorted constituted a legitimate union objective, union thugs have been getting a free pass on violence and threats such as what occurred in June 2014.

Perhaps inspired by their Teamsters contract at the time driving trucks for the movie “Black Mass,” starring Johnny Depp as infamous Boston mobster Whitey Bulger, four Teamsters Local 25 members decided that the Emmy-winning “Top Chef” show shouldn’t be permitted to film on union turf unless union bosses got their cut.

The show’s non-union staff does whatever driving is necessary, so there was no need to hire forced dues-paying Teamsters members for the positions, but that didn’t stop Teamsters goons John Fidler, Michael Ross, Robert Cafarelli and Daniel Redmond from trying.

“Top Chef” had originally planned to film an episode at the Omni Parker House Hotel and the Menton restaurant in Boston itself. However, these two venues told “Top Chef” it was no longer welcome after receiving calls in advance of the scheduled filming from Ken Brissette. Mr. Brissette, an appointee of union-label Boston Mayor Marty Walsh, had informed “Top Chef” they would be harassed by a Teamster mob if they refused union militants’ request.

Consequently, the shoot was moved to the Steel & Rye restaurant in the suburb of Milton. There, as Assistant U.S. Attorney Laura Kaplan told jurors August 1, the entire cast and crew as well as restaurant patrons faced a “gauntlet” of Teamster verbal and physical attacks. Union goons threatened to assault and even kill cast and crew members as a means of “persuading” the show’s producers to change their minds and sign a union contract.

Members of the production crew were assaulted. Tires were slashed. Sexist, racist and homophobic slurs were hurled. According to multiple reports model, cookbook author, and “Top Chef” host Padma Lakshmi was threatened: “We’re gonna bash that pretty face in, you [expletive] whore!”

The threats and violence were all documented by witnesses in the federal extortion trial which concluded on Aug. 15, 2017. Despite it all, the four Teamsters members were still acquitted because of a loophole in federal anti-extortion law for union activities.

In the trial, the union bullies’ lawyers never quite denied that the extortion, as Americans commonly understand the term, had occurred. Instead, Teamsters lawyers invoked the controversial precedent set by a 5-4 U.S. Supreme Court majority nearly 45 years ago in U.S. v. Enmons to evade jail time for their clients.

The Enmons decision exempts union officials and members from anti-racketeering and extortion laws, so long as union officials can prove their actions were “legitimate union objectives.” In this case those objectives were getting “Top Chef” to hire Teamsters drivers, even though its nonunion permanent crew already handled transportation. Kenneth Barron, one of the defense attorneys, explained the demands to the jury: “The union doesn’t have to take no for an answer.”

Union lawyers relied on the legal precedent set in Enmons. All their clients were trying to do, Mr. Barron insisted to the jury, was take jobs away from union-free workers and thus make them available for forced union dues-paying Teamsters. That seemed plausible enough to the jury, who on August 15 unanimously acquitted all four defendants on all charges.

This case is settled, but many Americans are left wondering how this possibly could be legal. How can such obvious extortion not be illegal just because a labor union is involved?

The only possible silver lining of the verdict is that it will help focus public attention on the need for Congress to adopt legislation overturning the misbegotten Enmons decision. Since 1997, the Freedom from Union Violence Act has been regularly introduced in Congress to do just that, with the 2017 version expected to be introduced on Capitol Hill shortly after Labor Day.

This common sense law has been stonewalled or voted down time after time by Big Labor-backed politicians but as the verdict in Boston shows, the Freedom from Union Violence Act is still desperately needed to restore equal justice under the law. The ugly violence, threats, and intimidation deployed in Boston by the four acquitted Teamsters ought to remain only in movies about mobsters, not as a legal weapon to be deployed by organized labor.

• Mark Mix is president of the National Right to Work Committee and National Right to Work Legal Defense Foundation.